Aromatic glycol ethers as writing monomers in holographic photopolymer formulations

Abstract

The invention relates to a photopolymer formulation comprising specific aromatic glycol ethers as writing monomers, matrix polymers and a photoinitiator. The invention further provides an unexposed holographic medium obtainable using an inventive photopolymer formulation, and an exposed holographic medium obtainable by exposing a hologram into an inventive unexposed holographic medium. The invention likewise provides a visual display comprising an inventive exposed holographic medium, for the use of an inventive exposed holographic medium for production of chip cards, identification documents, 3D images, product protection labels, labels, banknotes or holographic optical elements, and specific aromatic glycol ethers.

The invention claimed is: 
     
       1. A photopolymer formulation comprising
 D) as writing monomer at least one aromatic glycol ether of the general formula (I) 
 
       
         
           
           
               
               
           
         
         
           in which Aryl is a substituted aromatic radical, 
           wherein R1 is a radical of formula (II) and R2 is a radical of formula (III), or 
           wherein R1 is a radical of formula (III) and R2 is a radical of formula (II) 
         
       
       
         
           
           
               
               
           
         
         
           in which 
           R3 is an organic radical which has up to 6 carbon atoms and may contain oxygen and/or sulphur atoms, and 
           R4 is a radical selected from the group of —H, —CH3; 
         
         E) matrix polymers; 
         F) a photoinitiator, and
 wherein the Aryl radical is substituted by 1 to 5 identical or different substituents selected from the group consisting of n-alkyl, branched alkyl, alkyloxy, phenyl, methylphenyl, ethylphenyl, thiomethylphenyl, methoxyphenyl, biphenyl, benzyl, phenylalkyl, naphthyl, methylthiyl, ethylthiyl, alkylthiyl, alkylthioalkyl, phenoxy, phenylthiyl, napthylthiyl, fluorine, chlorine, bromine and iodine. 
 
       
     
     
       2. The photopolymer formulation according to  claim 1 , wherein the Aryl radical comprises 5 to 21 carbon atoms and/or heteroatoms in the aromatic system. 
     
     
       3. The photopolymer formulation  claim 1 , wherein the Aryl radical is selected from the group consisting of phenyl, methylphenyl, ethylphenyl, thiomethylphenyl, methoxyphenyl, biphenyl and naphthyl. 
     
     
       4. The photopolymer formulation according to  claim 1 , wherein R3 is a radical selected from the group consisting of —CH2-, —CH2CH2-, —CH(CH3)CH2-, —CH2CH(CH3)-, —CH2CH2CH2-, —CH2CH2CH2CH2-, —CH2CHOCH2CH2-, —CH2CH2OCH2CH2OCH2CH2-. 
     
     
       5. The photopolymer formulation according to  claim 1 , wherein the R1 radical is a radical of the formula (II) and the R2 radical is a radical of the formula (III), where the R3 radical is a—CH2CH2- radical. 
     
     
       6. The photopolymer formulation according to  claim 1 , wherein the R1 radical is a radical of the formula (III) and the R2 radical is a radical of the formula (II), where the R3 radical is a—CH2CH2- radical. 
     
     
       7. The photopolymer formulation according to  claim 1 , wherein the matrix polymers B) have been crosslinked. 
     
     
       8. The photopolymer formulation according to  claim 1 , wherein the matrix polymers are polyurethanes. 
     
     
       9. The photopolymer formulation according to  claim 1 , wherein it additionally comprises a monomeric fluoroethane. 
     
     
       10. The photopolymer formulation according to  claim 9 , wherein the fluorourethane comprise at least one compound of the formula (IV) 
       
         
           
           
               
               
           
         
         in which m≥1 and m≤8 and R7, R8, R9 are each independently hydrogen or linear, branched, cyclic or heterocyclic organic radicals which are unsubstituted or else optionally substituted by heteroatoms, where preferably at least one of the R7, R8, R9 radicals is substituted by at least one fluorine atom and, more preferably, R7 is an organic radical having at least one fluorine atom. 
       
     
     
       11. A holographic medium comprising the photopolymer formulation according to  claim 1 . 
     
     
       12. The holographic medium according to  claim 11  into which at least one hologram has been exposed. 
     
     
       13. The holographic medium according to  claim 12 , wherein the hologram is a reflection, transmission, in-line, off-axis, full-aperture transfer, white light transmission, Denisyuk, off-axis reflection or edge-lit hologram, or else a holographic stereogram, preferably a reflection, transmission or edge-lit hologram. 
     
     
       14. A visual display comprising a holographic medium according to  claim 12 . 
     
     
       15. The holographic medium according to  claim 12  which is applied to chip cards, identification documents, 3D images, product protection labels, labels, banknotes, holographic optical elements, or visual displays.